Plywood press loaders



July 24, 1956 R. A. MULLER 2,755,832

FLYWOOD PRESS LOADERS Filed June 16, 1951 4 Sheets-Sheet l July 24, 1956 R. A. MULLER PLYWOOD PRESS LOADEIRS 4 Sheets-Sheet 2 Filed June 16, 1951 WW KM 25/ @V ZZ QI.

July 24, 1956 R. A. MULLER 2,755,832

PLYWOOD PRESS LOADERS Filed June 16, 1951 4 Sheets-Sheet 3 23 /Z 7 W y ig gig lv cz enzoy m y'zgggg y 1956 R. A. MULLER 2,755,832

PLYWOOD PRESS LOADERS Filed June 16, 1951 4 Sheets-Sheet 4 j-a evzzar' 5 1 WMGu .M

53 WW WM United States Patent PLYWOOD PRESS LOADERS Robert A. Muller, New London, N. H., assignor to Atlas Plywood Corporation, Boston, Mass., a corporation of Massachusetts Application June 16, 1951, Serial No. 231,998 11 Claims. (Cl. 144-281) This invention relates to the manufacture of plywood panels and to a combination plywood press and press loading apparatus by means of which plywood materials may be more efiiciently and economically handled and produced in relatively large scale operations.

The general process of producing such panels includes the steps of assembling the desired number of sheets of veneer cut to size in superimposed relation, certain sur faces of the sheets being coated with glue or other adhesive, and the sheets being arranged in the desired manner to produce an individual panel. These operations are repeated and a series of the panels are usually placed in a press loading mechanism which is designed to simultaneously feed the panels into a plywood press.

In carrying out such operations it is found to be highly important to protect the panels from exposure to heat prematurely in order to avoid an inferior quality product. Trouble in this way has developed in the past from having the loading apparatus too close to the press where considerable heat is maintained. A flow of heat from the.

press may, for example, either directly affect forwardly exposed portions of the glue coated panels, causing a precure, or the loader plates may become excessively heated, producing somewhat the same result.

To avoid exposure to heat and to allow time to properly stack plies, prior art devices of which I am aware have required that the press loading apparatus be provided as a separate unit which can be moved toward and away from the front of the plywood press during loading operations. From their very nature these prior art loading mechanisms are necessarily cumbersome to handle and thus involve a loss of valuable time. Moreover, they are complicated and very expensive to build and maintain and all of these factors have been found to undesirably increase the cost of manufacture of the plywood panels.

The present invention aims to deal with the problems indicated and to devise a combination plywood p'ress and press loading structure with a view to providing a simpler construction; one which will be much less expensive to manufacture; more economical to operate; and one which,

at the same time, will afford a degree of flexibility and safety in operation not present in prior art constructions.

These and other objects and novel features will be morefully understood and appreciated from the following description of a preferred embodiment of the invention selected for purposes of illustration and shown in the accompanying .drawings, in which Fig. 1 is an isometric view of the combination plywood press and press loader construction of the invention;

Fig. 2 is a fragmentary view, in vertical section ,illustrating details of the press and loader feeding mechanism,

and further showing a heat barrier member in one position of adjustment therein;

Fig. 3 is a fragmentary sectional view, somewhat similar to Fig. 2, but further illustrating theheat barrier member in another position of adjustment which it assumes in the feeding cycle;

Fig. 4 is a fragmentary sectional view corresponding-to Patented July 24, 1956 2 Figs. 2 and 3, illustrating still a third position assumed by the heat barrier member in the course of a press load ing operation;

Fig. 5 is a view, mainly in vertical cross-section, illustrating feeding mechanism for the press loader section of the apparatus of the invention;

Fig. 6 is a sectional view taken approximately on the line 6-6 of Fig. 5;

Fig. 7 is a perspective view further illustrating details of the panel feeding mechanism shown in Fig. 5;

Fig. 8 is a cross-section taken on the line 8-8 of Fig. 5;

Fig. 9 is a sectional view of one of the lugs used on the chains for driving the straps that operate the panel pushing bars;

Fig. 10 is a diagrammatic view showing the combination press loader and press mechanism of the invention as viewed from one side thereof and further indicating,

means for raising and lowering the heat barrier member shown in Figs. 2, 3 and 4;

Fig. 11 is another diagrammatic view of the apparatus shown in Fig. 10 and further indicating electrical control means associated therewith; Fig. 12 is a diagrammatic view of the apparatus shown in Figs. 10 and 11, and further indicating a car for conveying plies of material into proximity to the loader;

Fig. 13 is a plan view of the operating mechanism for the chains above referred to;

Fig. 14 is a front elevation of said operating mechanism; and I Fig. 15 is a diagrammatic view of the wiring utilized in operating they present device.

The improved loader and press combination of the invention is based upon the novel concept of arranging a loader mechanism in juxtaposition to the front side of a press and securing this loader mechanism in fixed relationship to the press so that the loader becomes an integral part of the press, and the practice of movingthe loader mechanism toward and away from the press is;

completely eliminated with much saving in time and labor; being realized. I

In thus locating a loader mechanism in relatively close; proximity to the press, it is necessary to maintain the press loader plates relatively cool and, to do this, I provide a narrow space between the plates and the press and I combine with the press and attached loader mechanisma heat barrier member adjustably disposed in the space indicated between these two members in a positionto thermally isolate the press loader mechanism,'when-thisis desired.

Also in securing together the press and loader mecha nism, and in providing means for thermally shielding theloader mechanism, certain other problems arise in connection with actually feeding the panels of plywood from the press mechanism into the press itself. I have devised a special form of feeding mechanism which is arranged in such cooperative relationship with respect to the pressloader and heat barrier mechanism, that botha forward and return travel of the mechanism can be carried out without interference with the standard type of press con-,

struction.

The press mechanism with which the loader unit is used may be any one of several forms available commercially. A typical construction is shown in Pat. No. 2,420,813,

granted May 30, 1947. These presses are constructed and operated as described in said patent and comprise a series of plates or platens arranged, one above another, with stepped supports for holding the plates in properly; spaced relationship when the press is open for the intro? duction of. panels between the plates. An hydraulically operated plunger positioned underneath the series of plates.

is operated at the desired-time to lift the plates successively" an their'supports, and'finally to press them together with theiforce necessary to apply the desired degree of pressure to the plywood panelsinterposed between adjacent plates. .Theplatensor plates are;heatedmndtusuallytthe adhesive between thesheets ofveneer is olianaturc which requires curing so that suitable pressure and heat. is. applied to effect the desiredchemicalchange.imthe' adhesivemate'rial. A'few of theplatesof such.a pre ss.ar-e. shownin Figs.'1,'2, 3 and 4 and aredenoftedzbydhe. numeral;2.

A typical arrangement :by nicansof, which .panels-.-are brought up to 'the combination press .and loading mechanism,.has.been shown diagrammaticallyliniFig. 12,'the press being indicated by numeral '3;..the loader indicated generally by nurneral 4; and a car" i'n'dicatedlby numeral 5 mounted on tracks'. "The carb'rings the stacks of plywood assemblies tothe loader where they .areplaced, either automatically or by' hand,'into..theshelves. of-fthe loader and are "later transferredsimultaneously to the press. 3. v I 7 "Considering in greater. de'tail'fthe preferred embodiment of theinven'tion shownin the drawings, the loader con Silll'CiiOtl comprises a steel frame in which a series of shelves'are mounted. The shelves maybe of any suitable type and, as shown, consistjsimply offfiat metal sheets'71supported on brackets consistingof angle irons 9 which, in" turn, are mounted on corner uprights 8. While the size of the shelves may be ma'de'to suit therequirements of individual situations, typical dimensions of shelves"whichhaveibeen successfully used are widths of 3 to 4feet'and lengths'of'6 to 8 feet.

*I'naccordance with'the inventionl locate'the above described loader frame in juxtapositionito'the frontnf the'press 3 such-that-a relatively narrowspace or vertical well is left between these units, and I solidlysecureflte loaderframeinfixcd relationship" to} the press in some suitable manner. I may resorrto-weldingonl may .bolt the two 'units'either directly to oneanother,;or I 'may employother means. For example, in the preferred form of the invention shown in the drawingslprovide 'a pair of vertical channel members,'oneof which has been shown in Fig. 1 and-denoted by the letter' U. One'side of the channel "member" U is welded to an adjacent corner '8 'of the loader-frame, and an opposite'sideofthe channel'U is secured to an adjacent surface of'the: press 3.

With this channel arrangement a relatively narrow space is le'ft between'the units, as maybe more'clearly seen "from-"an inspection (Sf-Figs. 2'to 4,-inclusive, and in' this space I- have mounted 'a' heat barrier memben H consisting of a rigid sheet of insulatingmaterialysuch as aluminum orsomeother suitable substance. "Thememu ber H is slidably received in the two channelmembers'U inaposition'such that it maybe raised'or'lowere'di "To cari y out the latterfunction I provide a winch orpulley arrangement P operated from an electrical motor "M mounted on a support "fixed above v: the loader frame, as suggested infFig. 10.

"When the heat barrier member H is in-a' fully lowered position in the channelmembers a-very. substantial thermal shieldingefiect can be realized, andI'find'that'byusing-"a thickness'of aluminumof approximately'three=eighths of an inch, for examplefl arn=enabled tointerrnpt flo'vv-of heatfrom' the'press to the sheets'ofiplywood in the loa'der su'fiiciently to avoidany danger oi prematurely curing the glue coating at the frontedges of the plies, and the temperature of the metal sheets 7 can be constantly-maintained 'at a satisfactorily low level.

It will be apparent that by loading the plies into the loader mechanism insuch close proximity toithepress, it'becomes possible to carry :out .a much more eflicient transfer of sheets from the loader frame to the press with a material savingintime, aswell as completelimination of any likelihood of over-curing th'efront edgesof the plies.

lnia'ddition to .ithesenovel resultsghoweven .Lfindthat I am able ..to.rea1ize still other uneitpectedtbenefits of an important nature. Thus, in conventional types of loaders,

loading opertion, to stop at some point and move to a position in back of the loader where the inner edges of the plies may be inspected in order to make sure that they do not extend too far inwardly and are arranged in proper alignment with one another for delivery to the press.

In actual practical application oftheheat barrier arrangement of the invention, it turns out that the need for checking is eliminated since the-heat barrier -H'in';its lowered position can be made use of as an alignmentior register elements which operates to prevent the plies'from being advanced too'far forwardly during theloading operation. As a result a very appreciable speeding up of this part of the handling-operationis'realized and in the course of repeated loading cycles such faster handling necessarily becomes highly advantageous from an economic standpoint. I p

The heat barrier member Halso. has the virtue. of introducing certain vdesirable safetyieatures into the press loading operation. -.It is often found to "bathe case that workmen may be inadvertently fail. to accuratelycheck the register or alignmentofiront edges of the pliesafter they have" been delivered from .conventionalttyPes of press loaders. If thedpressl in this condition is operated-as sometimes happens. with -.some.of theplies out of register, there may occur'both a waste of. stock andalso possible damage Tto the loading equipment with; a. loss. of time.

In this connection it is pointed outthat by properly using the heat barrierH of the-invention; .all plies .will have been advanced -forwardlyinto.the,press beyond a point where interference 'can't'ake place, and mustbe so in order' for the'heat barrier member to be lowered into its bottom" position.

To take-thejfullest possible advantageof thissituation, I have also provided. suitabieilimit switch means 'forlcontrolling the operation of the" loading and. press. mechanisms so'thatthe movement of thehydraulic ram ofthe press into 'araised position cannot occur until the barrierflH is inn-fully lowered position.

Thus, "oneerrangement for accomplishing this result has been illustratedin Fig. ll where a normally open switch S1 is connected'into the starting circuit-fortthe motor M. This switch alsocontrols operation 'of the loader mechanism through the motor'32, as willbefhereinafter described. The connectionof'limit switchfSl'is such that "it holds open the circuit .until the switch .is closed byarrival ofthe barrier H in its top orfully raised position,

' Another-normally.openlimit switch S2'is arranged to be {closedby movement .of the'barrier 1H into .its fully loweredposition and this switch isconnected to thestarter ofthe pressso that the operation-of .closing the .press cannot'be started until after the door 'has 'beenclosed.

The rsafetysfeature thus realized will readily heap parent, andinactual' practice ithas been found :thaLthis safety feature results in verysubstantial savings in the cost andr'maintenance of the equipment taken over a period 'of time.

Attention is further idirected to thC [feeding mechanism 4 ofthe inventionfand in this connection also to .the fact that an essential requirement in a'loader feeding mechanism is that all of .the plies shouldlbe advanced into the.

press'at substantially the same time in order to ensure uniformity of treatmentof theplies. ilnpriorart devices of whichiIam aware su'chan operation. has been accomplished by means (if pusher bars. These bars are-driven through the aid of horizontally ,spacedeapart -.spr.ocltet gears and chains engaging the ,gears. .Eachpusher bar requires a separate set of sprocketggears and-chainstcapable of .heing .reversed .in direction.

Such .an arrangement .is necessarily \of acornplicated and cumbersome .characterand, .moreover, zist-notgrractical for I use with a construction in which the loadenimfixedinjuxtw positiontothemress, such assettorth -in thegsiesentdnrtention, owing to the fact that it is not feasible to mount sprocket gears and chain drive mechanisms directly on the press. One problem arises particularly. It is desirable in operating the press loader to push the feed bars well beyond the loader plates and completely into the press openings for a little distance, in any event, and in some cases all the way through these openings. Obviously sprockets and chains of prior art devices have definite limitations as to how far the pusher bars can be advanced when the loader is secured in juxtaposition to the press.

In the present invention I have devised a novel feed mechanism for a loader controlled by the limit switch S1 above referred to and especially designed to function with the combination of a press loader secured in juxtaposition to the press and having a movable heat barrier member adjustably disposed between them. By making use of compression type feed elements I am able to produce a forward movement of pusher bars without resorting to a horizontal sprocket chain drive and this movement is not limited in its length of stroke to any particular point in the press openings.

The novel feed mechanism of the invention has been shown in greater detail in Figs. 1, 5, 6, 7 and 8. As noted above, the shelves 7 of the loader are supported on angle irons 9 at the front section of the frame. In addition, I have provided a set of brackets 9, Figs. 2 to 4, inclusive, located at the back of the loader where they support the rearward edges of the shelves 7. Also associated with the brackets 9 and 9' are guide plates 10 which are located along two opposite sides of the loader frame adjacent to each set of shelves 7 in position to limit any endwise movement of the assemblies of veneer sheets.

It is pointed out that these assemblies come to the loader in the form of what may be termed panels, each consisting of sheets of veneer, the number of sheets being usually between two and five. These assemblies have been produced following the coating of the proper surfaces of the sheets with adhesive so that after the pressing operation has been completed the desired number of plies in each panel will be secured firmly together. However, when the panels are brought to the loader, as for example, on the car 5, the plies for each panel are loosely assembled, but each panel is independent of its neighbor. If the operation of placing them in the shelves of the loader is to be performed by hand, then they are picked up, one or two at a time, by two workmen working together at opposite ends of the loader, each panel being slid edgewise in between the shelves.

Mounted in cooperating relationship with the guide plates 10 above respective shelves 7 are a plurality of feed elements or so-called pusher bars 11. Each one of these bars may conveniently consist of a strip of sheet metal folded into the form best shown in Figs. 5, such that the pusher bar presents an upright face a directed rearwardly to engage the plywood panels and an inclined front face b. In Fig. 1 only the inclined faces of the pusher bars appear, but the fact that they extend the entire length of the shelves is there illustrated.

To move the pusher bars back and forth across-their respective shelves, 1 have combined with them individual driving elements, each of which acts somewhat in the nature of a rack capable of operating as a rigid member in compression in one direction of pusher bar travel and capable of functioning as a flexible member in tension in an opposite direction of pusher bar travel.

These driving elements comprise a plurality of resilient metal tapes 12, each of which has secured to one side thereof an extremity of a respective pusher bar by means of a fastening 12a, as shown in Fig. 5. The'extreme end of each tape, however, preferably extends forwardly somewhat beyond the pusher bar, as indicated at 0 injFig. 5. Also provided is a driving unit for each strap 12, cornprising a wheel 13 provided with lugs d spaced around the outer periphery of the wheel to center andextend through correspondingly formed holes in the tapes 12. Cooperating with each wheel and tape element is a press roll 14 which bears on the tape and .holds the tape firmly against the wheel 13 so that no buckling at this point can take place. The press roll 14 has its central portion recessed to form an annular channel which permits passage of the lugs d therethrough as the tape element moves forwardly.

A vertical series of these wheels and press rolls are mounted on the outer sides of both of the corner standards 8, Fig. l, the nature of the mounting being more clearly illustrated in Fig. 6. Each wheel 13 is secured fast on a shaft 15, Fig. 6, supported in bearings mounted in the frame piece 8. This shaft also supports another sprocket wheel 16 at the outer side of the frame piece 8. The press roll 14 is mounted on a stationary shaft 17, Fig. 6.

Referring to Fig. 1, it will be seen that all of the sprockets 16 at the end of the loader nearest the observer are arranged to mesh with a sprocket chain 18 which is supported on upper and lower'sprocket wheels 20 and 21. Between adjacent sprockets 16 guide sprockets 22 are mounted to hold the chain in driving engagement with the sprockets 16.

The same arrangement is provided at the opposite end of the frame. Consequently, if the two sprocket chains are driven in unison, all of the rolls 13 which mesh directly with the straps 12 will also be driven in unison and, consequently, all of the feed bars 11 will be forced in the direction of the press across the shelves simultaneously and will push the plywood panels in contact with them through the loader and into the press at the same time. Fig. 5 shows these bars in full lines in one position assumed during their feeding movement.

While this movement is transmitted to each feed bar by a thrust exerted lengthwise of that section of the strap 12 between the rolls 13 and 14 and the bar, the strap is so supported that it is not allowed to buckle and, consequently, the bars are operated positively. Referring to Figs. 5 and 8 it will be observed that the guide plate 10 is one flange of an angle iron, the horizontal flange 10 of which is riveted to the edge of the shelf 7 but is spaced from that shelf by a thin metal strip 23, slightly thicker than the strap 12. Consequently, more than half of the width of this strap is confined, closely but slidably, between the shelf 7 and the plate 10', and it therefore is compelled to transmit the thrust imparted to it by the rolls 13 and 14 by compression.

When the motion of the driving sprocket 16 is reversed, all the feed bars 11 are moved simultaneously forward across the shelves to their initial positions at thev front of the press, but the force applied through each pair of rolls 13 and 14 to its respective strap 12 is, at

this time, a pull instead of a push. The free end portions of the straps are guided down through holes 34-34, Fig.

l, in one of the base frame members and into suitable chutes or casing members in the floor below. Figs. 2, 3 and 4 illustrate several different feeding positions assumed by one of the pusher bars in the course of one feeding cycle.

At the front of the loader an angle plate 24, best shown in Fig. 5, extends along'the entire front edge of each shelf where it assists in guiding the plywood sheets down on to the shelves as they are introduced into the space between adjacent shelves. Also, at the rearward end of each shelf another angular plate 25 is secured to it by means of an angle bar 26 where it deflects downward any forward edge of a panel which may be curled or spring upwardly.

The primary driving mechanism for the feed bars 11 isbest shown in Figs. 13 and 14. It comprises a shaft 27 mounted on the top of the frame of the loader and carrying the tWo sprocket wheels 2020 for driving the chains 18 at the opposite ends of the frame. This shaft is connected by two sprocket and chain drives 28-28 to the output shaft of a gear reduction unit 30 which, in

7 turn, is drive'n" through its' shaft connection '31 with the electric motor 32. .Thusbothsprocket 'chains18'are compelled to'revolve'in unison. The shaft 2'9, Fig. l, connects thetwo sprocket wheels 21 at the oppos'ite'ends of theframe.

Itshoul'd"'be observed'that the'loader and the press are secured together in fixed relationship to each other so that the upper surface of each shelf is always in alignment with the upper surface of its cooperating press platen or plate 2' when the press is in its open position. While theplatens'aremoved out of this relationship the shelves of theloader remain in permanently fixed positions, and the shelves of thepress always return'to their registering relationship with the shelves of the loader every time that thepressi's fully opened.

An outstanding advantage of the tape driving elements is thatthey can'be satisfactorily combined with a press and leader mechanism secured in fixed juxtaposition to one another with the tapes mounted in such cooperative relationship to these members that transfer of plies from the loader to the press can be carried out without interference with the heat barrier H which must necessarily be moved in and out of the space between the loader and press during the loading cycle. This freedom from interference is made possible by reason of the fact that the tapes can operatein compression in one direction and in tension in the opposite direction. Because they can operatein compression during the feed stroke they can be supplied with a driving force which is exerted from apoint well in back of thepress and, consequently, there is no interference between the press and the driving mechanism. w

On the otherhand, thefeed mechanism is not limited in its extent of travel and can readily enter into the openings between the press plies and, moreover, can actually feed all the vway through the openings, if desired. Because of this flexibility and greater range of operation the pusher bars may, if desired, be used to eject pressed panels'from the press before starting anew cycle. It will be apparent that the flexibility of the tapes allows them to be flexed at points where they leave the front of the press loader frame and thus may be guided downwardly in verticaloverlapping relation to one another through the .bottornslots in the frame out of the way of workmen when they are loading sheets into the front of the loader frame.

Control of the various operations of the machine is conveniently produced by electrical systems roughly similar to those used to control elevators and equipment of a like nature. This control may be such as to operate the loader automatically in accordance with a predetermined cycle, or the operation may be manually controlled. In the present instance this control system includes a switch 35, Fig. 1, provided with push buttons x, y, z, which operate through suitable relays to control the operation of the motor 32.

Assuming that the'cycle is to be controlled manually, and that the loader has been filled, the operator presses the top button x which starts up the motor 32 in a direction to cause the feed bars 11 to move in the direction of thepress, as above described, thus forcing the plywood panels in the loader into the press. When this transferring operation has proceeded to the desired point, it may be stopped by pressing the reverse button thus causing the motor to reverse its direction and, consequently, to return the feed bars to their initial positions at the front of the loader.

In an automatic cycle of operations the operator -initiates the cycle by pressing the top button x, as above described, but when the push bars have completed their backward "movement, a control lug 3'6 on the chain 18 strikes the operating arm of the lower limit switch 37. This "closes the reversing switch, thus reversing th'e'rnovement of the motor and, consequently, of the feed bars.

thcyliave returned to their initial positions "at "the front of the 'press, "theinmovement is stopped by the en agement of the upper lug 38, Fig 1, with the erating arm of the upper limit switch 40, which results in stopping the motor'and completing the cycle. In'this connection'it maybe pointed out that a reversal of the motor'is accomplished through a zero-speed plugging switch 3 2, Fig. l3, driven from the shaft to the motor 32. 'O'rdinarily these 'chainlugs and the limit switches are used because ofthe greater convenience and tlie'saving in time which they afford.

It at any time during the cycle of automatic operations it is desired to stop the motion of thefeed bars, thejbottom button z should be pressed which will inimedia'tely stop the motor and the mechanism operated by it.

One of the lugs used on the chain is shown in detail in Fig. 9. It comprises a cam member A having upper and lower inclined'surfaces to engagethe operating'lement of either of the limit switches, a cooperating rn'e'iru her 3, and a screw C for securing these two parts toa linkL'of the chain 18. Consequently, the timing df'the steps in the cycle 'controll'edby these lugs can be changed by-adju'sting'the lugs on the chain.

as above described. For the s ecific material mentioned,

- a thickness of'in'the neighborhood or .021 to .042 inch hasprovedsatisfactory.

The components ofth'e press loadnmechanismfdscribed are subject tomodification in various ways. For example, the barriei' member, which has been described in the specification as being movable in'a vertical plane by means of the hoisting mechanism'iridicated in the drawings, may also be arranged'to r'n'ovein other'wa'ys as, for' example, in a horizontal direction, in which case the barrier might normally be disposed at one side or the other of the press loader mechanism. I may also" desire to construct the door in sections, and in this connection'I may provide a door made up of two sections splitin the middle along avertical line of separation with each section being arranged to move inwardly and outwardly from opposite sides of the loader frame.

It -will be evident that combined loader and press apparatus made in accordance with this invention is relatively simple in construction and can be manufactured se nomically; it is also-economical to operate; and has proved extremely reliable. A further advantage of these units is their uniisual flexibility in operation. For example, such a machine willliandle all sizes and shapes of'plywood upto 'the maximum dimensions for whichitisdesigned'which has been'true of few, if any, prior'a'i't loade'rfs'ofWhichI have been able to learn.

'ltwillthu's b'e'seen that Ihave'provided a press loa'der combining the-featuresof a bendable rack or tape capable of transmitting compression ortextile forces with a'licat barrier member. I have further provided for the rack'o'r tape -rising in-an'essentially vertical path in front of the press lead r mechanism, in this way providing for free access trithe' press -l'oade'r for the operation of handling and loading plywood sheets from points in froritof the loader. The tape after moving along a verticalpath -is so arranged that it changes it's'direction of travel and moves along a horizontal .path. Presser bars are secured to individual tapes and in response to movement ofthe tapes are moved along a horizontal plane in both forward and rearward directions. The barrier member isso combined with the presser bars and bendable racks that it may act as a heat barrier to prevent .precuring of plywood sheets and asa mechanical barrier to assure correct juxtaposition of the edges o f the material to be loaded and pressed, thereby greatlyreducing the possibility of production errbrs'arfd' eliminatin the possibility of damage mine rr'ie'clfanis'm.

While I have herein shown and described a preferred embodiment of my invention, it will be evident that it may be embodied in other forms without departing from the spirit or scope thereof.

I claim:

1. In a plywood loader, in combination, a heated press assembly including a plurality of spaced plates arranged in superimposed relation, a loader rigidly fixed in side by side relation to the press and including a plurality of spaced shelves each in substantially the same plane as the adjacent press plate to permit the transfer of sheets of plywood from the shelves to a predetermined position on the adjacent press plates, said press plates and shelves having their adjacent marginal edges spaced to provide a well between the press and loader, a flat barrier structure supported above the well for vertical movement in said well between the press and loader to thermally insulate the loader from the press, and guide means for the barrier at each side of the well.

2. The structure according to claim 1, including means for moving the barrier vertically in said well and into and out of the path of movement of the plywood sheets; an electrical motor circuit including relay means for operating said press, and a switch in said circuit controlled by the position of the barrier for limiting the periods of operation of the press.

3. In combination, a plywood press, a loading apparatus fixed to and in spaced relation to the press, said press loading apparatus including a frame, a series of stationary shelves supported in said frame and adapted to receive sheets of plywood, a bar extending lengthwise of each of said shelves along the front edge thereof, two flexible driving members connected with opposite end portions of each of said bars, power driven mechanism operable through said flexible members to push said bars into the press to locate the sheets of plywood entirely within the press in substantially centered relationship therein, means at each side of each sheet overlying the flexible driving members to maintain same against buckling when operating to push said bars, a barrier movable into and out of e the space between the press and loader, and means for synchronizing the movement between the barrier and the bar.

4. In a plywood loader, in combination, a heated press assembly including a plurality of spaced plates arranged a in super-imposed relation, a loader rigidly fixed in side by side relation to the press and including a plurality of spaced shelves each in substantially the same plane as the adjacent press plate to permit the transfer of sheets of plywood from the shelves to a predetermined position on the adjacent press plates, said press plates and shelves having their adjacent marginal edges spaced to provide a well between the press and loader, the spacing between each adjacent pair of plates and shelves being substantially the same, a flat barrier structure supported above the Well for vertical movement in said well between the press and loader to thermally insulate the loader from the press, and guide means for the barrier at each side of the well, said guide means closing the vertical side of the Well.

5. In a plywood loader, in combination, a heated press assembly including a plurality of spaced plates arranged in super-imposed relation, a loader rigidly fixed in side by side relation to the press and including a plurality of spaced shelves each in substantially the same plane as the adjacent press plate to permit the transfer of sheets of plywood from the shelves to a predetermined position on the adjacent press plates, said press plates and shelves having their adjacent marginal edges spaced to provide a well between the press and loader, the spacing between each adjacent pair of plates and shelves being substantially the same, a fiat barrier structure supported above the well for vertical movement in said well between the press and loader to thermally insulate the loader from the press, guide means for the barrier at each side of the well, said guide means closing the vertical sides of the well, bars lying transversely across each shelf, power driven flexible driving means for each bar, and guide means overlying the flexible driving means for preventing buckling during operation.

6. The substance of claim 5 characterized in that the overlying guide means includes inner flat faces for engaging the side edges of plywood moving on said shelves.

7. A structure according to claim 1, including channel members for slidably supporting the heat barrier in substantially sealed relationship with respect to the front of the press, and means for vertically moving the heat barrier in to and out of the path of movement of the plywood sheets.

8. A structure as defined in claim 1, in which the heat barrier member comprises a rigid body adapted, in a closed position, to extend vertically between the frame and press in such close proximity to the edges of the said shelves as to constitute a stop for the plywood sheets.

9. A plywood press loader according to preceding claim 3, in which said flexible driving members are straps and said power driven mechanism includes two series of sprocket wheels positioned at opposite ends of said frame and meshing with the straps to drive them in one direction by pushing them and in the opposite direction by pulling them.

10. A plywood press loader according to preceding claim 3, in which said flexible driving members are straps, said machine including means defining guideways in which the respective straps run and the Walls of which guideways support said straps against buckling during the periods in which they push said bars.

11. A press loader apparatus of the character described, comprising a frame, a bendable rack capable of transmitting compressive or tensile forces, said bendable rack being supported in the frame and adapted to move through a substantially vertical path at points externally of the frame and in close proximity thereto for the purpose of providing free access to the front of the loader frame, said bendable rack being constrained for movement through the frame along a horizontal path, pusher bars attached to the bendable rack and movable in response to said rack in both forward and rearward directions relatively to the frame, in combination with a flat plate like barrier slidable to a position closely adjacent to the frame and movable with respect to the press loader frame to provide a heat barrier adapted to prevent precuring of plywood sheets in the press loader, said barrier member further functioning to assure correct juxtaposition of the edges of the plywood sheets to be pressed.

References Cited in the file of this patent UNITED STATES PATENTS 475,540 Coze May 24, 1892 1,291,522 Holmested Jan. 14, 1919 1,516,435 Houghton et al. Nov. 18, 1924 2,127,278 Welch Aug. 16, 1938 2,183,599 Welch Dec. 19, 1939 2,376,457 Skoog May 22, 1945 2,390,159 Laucks et al. Dec. 4, 1945 2,420,813 Camerota May 20, 1947 2,552,743 Simpson May 15, 1951 

